/*
 * RSA, a suite of routines for performing RSA public-key computations in JavaScript.
 * Copyright 1998-2005 David Shapiro.
 */

const window = {};

(function ($w) {
  if (typeof $w.RSAUtils === 'undefined') var RSAUtils = $w.RSAUtils = {}

  const biRadixBase = 2
  const biRadixBits = 16
  const bitsPerDigit = biRadixBits
  const biRadix = 1 << 16 // = 2^16 = 65536
  const biHalfRadix = biRadix >>> 1
  const biRadixSquared = biRadix * biRadix
  const maxDigitVal = biRadix - 1
  const maxInteger = 9999999999999998

  // maxDigits:
  // Change this to accommodate your largest number size. Use setMaxDigits()
  // to change it!
  //
  // In general, if you're working with numbers of size N bits, you'll need 2*N
  // bits of storage. Each digit holds 16 bits. So, a 1024-bit key will need
  //
  // 1024 * 2 / 16 = 128 digits of storage.
  //
  let maxDigits
  let ZERO_ARRAY
  let bigZero; let
    bigOne

  const BigInt = $w.BigInt = function (flag) {
    if (typeof flag === 'boolean' && flag == true) {
      this.digits = null
    } else {
      this.digits = ZERO_ARRAY.slice(0)
    }
    this.isNeg = false
  }

  RSAUtils.setMaxDigits = function (value) {
    maxDigits = value
    ZERO_ARRAY = new Array(maxDigits)
    for (let iza = 0; iza < ZERO_ARRAY.length; iza++) ZERO_ARRAY[iza] = 0
    bigZero = new BigInt()
    bigOne = new BigInt()
    bigOne.digits[0] = 1
  }
  RSAUtils.setMaxDigits(20)

  // The maximum number of digits in base 10 you can convert to an
  // integer without JavaScript throwing up on you.
  const dpl10 = 15

  RSAUtils.biFromNumber = function (i) {
    const result = new BigInt()
    result.isNeg = i < 0
    i = Math.abs(i)
    let j = 0
    while (i > 0) {
      result.digits[j++] = i & maxDigitVal
      i = Math.floor(i / biRadix)
    }
    return result
  }

  // lr10 = 10 ^ dpl10
  const lr10 = RSAUtils.biFromNumber(1000000000000000)

  RSAUtils.biFromDecimal = function (s) {
    const isNeg = s.charAt(0) == '-'
    let i = isNeg ? 1 : 0
    let result
    // Skip leading zeros.
    while (i < s.length && s.charAt(i) == '0') ++i
    if (i == s.length) {
      result = new BigInt()
    }
    else {
      const digitCount = s.length - i
      let fgl = digitCount % dpl10
      if (fgl == 0) fgl = dpl10
      result = RSAUtils.biFromNumber(Number(s.substr(i, fgl)))
      i += fgl
      while (i < s.length) {
        result = RSAUtils.biAdd(
          RSAUtils.biMultiply(result, lr10),
          RSAUtils.biFromNumber(Number(s.substr(i, dpl10))),
        )
        i += dpl10
      }
      result.isNeg = isNeg
    }
    return result
  }

  RSAUtils.biCopy = function (bi) {
    const result = new BigInt(true)
    result.digits = bi.digits.slice(0)
    result.isNeg = bi.isNeg
    return result
  }

  RSAUtils.reverseStr = function (s) {
    let result = ''
    for (let i = s.length - 1; i > -1; --i) {
      result += s.charAt(i)
    }
    return result
  }

  const hexatrigesimalToChar = [
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
    'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
    'u', 'v', 'w', 'x', 'y', 'z',
  ]

  RSAUtils.biToString = function (x, radix) { // 2 <= radix <= 36
    const b = new BigInt()
    b.digits[0] = radix
    let qr = RSAUtils.biDivideModulo(x, b)
    let result = hexatrigesimalToChar[qr[1].digits[0]]
    while (RSAUtils.biCompare(qr[0], bigZero) == 1) {
      qr = RSAUtils.biDivideModulo(qr[0], b)
      digit = qr[1].digits[0]
      result += hexatrigesimalToChar[qr[1].digits[0]]
    }
    return (x.isNeg ? '-' : '') + RSAUtils.reverseStr(result)
  }

  RSAUtils.biToDecimal = function (x) {
    const b = new BigInt()
    b.digits[0] = 10
    let qr = RSAUtils.biDivideModulo(x, b)
    let result = String(qr[1].digits[0])
    while (RSAUtils.biCompare(qr[0], bigZero) == 1) {
      qr = RSAUtils.biDivideModulo(qr[0], b)
      result += String(qr[1].digits[0])
    }
    return (x.isNeg ? '-' : '') + RSAUtils.reverseStr(result)
  }

  const hexToChar = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    'a', 'b', 'c', 'd', 'e', 'f']

  RSAUtils.digitToHex = function (n) {
    const mask = 0xf
    let result = ''
    for (i = 0; i < 4; ++i) {
      result += hexToChar[n & mask]
      n >>>= 4
    }
    return RSAUtils.reverseStr(result)
  }

  RSAUtils.biToHex = function (x) {
    let result = ''
    const n = RSAUtils.biHighIndex(x)
    for (let i = RSAUtils.biHighIndex(x); i > -1; --i) {
      result += RSAUtils.digitToHex(x.digits[i])
    }
    return result
  }

  RSAUtils.charToHex = function (c) {
    const ZERO = 48
    const NINE = ZERO + 9
    const littleA = 97
    const littleZ = littleA + 25
    const bigA = 65
    const bigZ = 65 + 25
    let result

    if (c >= ZERO && c <= NINE) {
      result = c - ZERO
    } else if (c >= bigA && c <= bigZ) {
      result = 10 + c - bigA
    } else if (c >= littleA && c <= littleZ) {
      result = 10 + c - littleA
    } else {
      result = 0
    }
    return result
  }

  RSAUtils.hexToDigit = function (s) {
    let result = 0
    const sl = Math.min(s.length, 4)
    for (let i = 0; i < sl; ++i) {
      result <<= 4
      result |= RSAUtils.charToHex(s.charCodeAt(i))
    }
    return result
  }

  RSAUtils.biFromHex = function (s) {
    const result = new BigInt()
    const sl = s.length
    for (let i = sl, j = 0; i > 0; i -= 4, ++j) {
      result.digits[j] = RSAUtils.hexToDigit(s.substr(Math.max(i - 4, 0), Math.min(i, 4)))
    }
    return result
  }

  RSAUtils.biFromString = function (s, radix) {
    const isNeg = s.charAt(0) == '-'
    const istop = isNeg ? 1 : 0
    let result = new BigInt()
    let place = new BigInt()
    place.digits[0] = 1 // radix^0
    for (let i = s.length - 1; i >= istop; i--) {
      const c = s.charCodeAt(i)
      const digit = RSAUtils.charToHex(c)
      const biDigit = RSAUtils.biMultiplyDigit(place, digit)
      result = RSAUtils.biAdd(result, biDigit)
      place = RSAUtils.biMultiplyDigit(place, radix)
    }
    result.isNeg = isNeg
    return result
  }

  RSAUtils.biDump = function (b) {
    return (b.isNeg ? '-' : '') + b.digits.join(' ')
  }

  RSAUtils.biAdd = function (x, y) {
    let result

    if (x.isNeg != y.isNeg) {
      y.isNeg = !y.isNeg
      result = RSAUtils.biSubtract(x, y)
      y.isNeg = !y.isNeg
    }
    else {
      result = new BigInt()
      let c = 0
      let n
      for (let i = 0; i < x.digits.length; ++i) {
        n = x.digits[i] + y.digits[i] + c
        result.digits[i] = n % biRadix
        c = Number(n >= biRadix)
      }
      result.isNeg = x.isNeg
    }
    return result
  }

  RSAUtils.biSubtract = function (x, y) {
    let result
    if (x.isNeg != y.isNeg) {
      y.isNeg = !y.isNeg
      result = RSAUtils.biAdd(x, y)
      y.isNeg = !y.isNeg
    } else {
      result = new BigInt()
      let n; let
        c
      c = 0
      for (var i = 0; i < x.digits.length; ++i) {
        n = x.digits[i] - y.digits[i] + c
        result.digits[i] = n % biRadix
        // Stupid non-conforming modulus operation.
        if (result.digits[i] < 0) result.digits[i] += biRadix
        c = 0 - Number(n < 0)
      }
      // Fix up the negative sign, if any.
      if (c == -1) {
        c = 0
        for (var i = 0; i < x.digits.length; ++i) {
          n = 0 - result.digits[i] + c
          result.digits[i] = n % biRadix
          // Stupid non-conforming modulus operation.
          if (result.digits[i] < 0) result.digits[i] += biRadix
          c = 0 - Number(n < 0)
        }
        // Result is opposite sign of arguments.
        result.isNeg = !x.isNeg
      } else {
        // Result is same sign.
        result.isNeg = x.isNeg
      }
    }
    return result
  }

  RSAUtils.biHighIndex = function (x) {
    let result = x.digits.length - 1
    while (result > 0 && x.digits[result] == 0) --result
    return result
  }

  RSAUtils.biNumBits = function (x) {
    const n = RSAUtils.biHighIndex(x)
    let d = x.digits[n]
    const m = (n + 1) * bitsPerDigit
    let result
    for (result = m; result > m - bitsPerDigit; --result) {
      if ((d & 0x8000) != 0) break
      d <<= 1
    }
    return result
  }

  RSAUtils.biMultiply = function (x, y) {
    const result = new BigInt()
    let c
    const n = RSAUtils.biHighIndex(x)
    const t = RSAUtils.biHighIndex(y)
    let u; let uv; let
      k

    for (let i = 0; i <= t; ++i) {
      c = 0
      k = i
      for (j = 0; j <= n; ++j, ++k) {
        uv = result.digits[k] + x.digits[j] * y.digits[i] + c
        result.digits[k] = uv & maxDigitVal
        c = uv >>> biRadixBits
        // c = Math.floor(uv / biRadix);
      }
      result.digits[i + n + 1] = c
    }
    // Someone give me a logical xor, please.
    result.isNeg = x.isNeg != y.isNeg
    return result
  }

  RSAUtils.biMultiplyDigit = function (x, y) {
    let n; let c; let
      uv

    result = new BigInt()
    n = RSAUtils.biHighIndex(x)
    c = 0
    for (let j = 0; j <= n; ++j) {
      uv = result.digits[j] + x.digits[j] * y + c
      result.digits[j] = uv & maxDigitVal
      c = uv >>> biRadixBits
      // c = Math.floor(uv / biRadix);
    }
    result.digits[1 + n] = c
    return result
  }

  RSAUtils.arrayCopy = function (src, srcStart, dest, destStart, n) {
    const m = Math.min(srcStart + n, src.length)
    for (let i = srcStart, j = destStart; i < m; ++i, ++j) {
      dest[j] = src[i]
    }
  }

  const highBitMasks = [0x0000, 0x8000, 0xC000, 0xE000, 0xF000, 0xF800,
    0xFC00, 0xFE00, 0xFF00, 0xFF80, 0xFFC0, 0xFFE0,
    0xFFF0, 0xFFF8, 0xFFFC, 0xFFFE, 0xFFFF]

  RSAUtils.biShiftLeft = function (x, n) {
    const digitCount = Math.floor(n / bitsPerDigit)
    const result = new BigInt()
    RSAUtils.arrayCopy(
      x.digits,
      0,
      result.digits,
      digitCount,
      result.digits.length - digitCount,
    )
    const bits = n % bitsPerDigit
    const rightBits = bitsPerDigit - bits
    for (var i = result.digits.length - 1, i1 = i - 1; i > 0; --i, --i1) {
      result.digits[i] = ((result.digits[i] << bits) & maxDigitVal)
                         | ((result.digits[i1] & highBitMasks[bits])
                          >>> (rightBits))
    }
    result.digits[0] = ((result.digits[i] << bits) & maxDigitVal)
    result.isNeg = x.isNeg
    return result
  }

  const lowBitMasks = [0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F,
    0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF,
    0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF]

  RSAUtils.biShiftRight = function (x, n) {
    const digitCount = Math.floor(n / bitsPerDigit)
    const result = new BigInt()
    RSAUtils.arrayCopy(
      x.digits,
      digitCount,
      result.digits,
      0,
      x.digits.length - digitCount,
    )
    const bits = n % bitsPerDigit
    const leftBits = bitsPerDigit - bits
    for (let i = 0, i1 = i + 1; i < result.digits.length - 1; ++i, ++i1) {
      result.digits[i] = (result.digits[i] >>> bits)
                         | ((result.digits[i1] & lowBitMasks[bits]) << leftBits)
    }
    result.digits[result.digits.length - 1] >>>= bits
    result.isNeg = x.isNeg
    return result
  }

  RSAUtils.biMultiplyByRadixPower = function (x, n) {
    const result = new BigInt()
    RSAUtils.arrayCopy(x.digits, 0, result.digits, n, result.digits.length - n)
    return result
  }

  RSAUtils.biDivideByRadixPower = function (x, n) {
    const result = new BigInt()
    RSAUtils.arrayCopy(x.digits, n, result.digits, 0, result.digits.length - n)
    return result
  }

  RSAUtils.biModuloByRadixPower = function (x, n) {
    const result = new BigInt()
    RSAUtils.arrayCopy(x.digits, 0, result.digits, 0, n)
    return result
  }

  RSAUtils.biCompare = function (x, y) {
    if (x.isNeg != y.isNeg) {
      return 1 - 2 * Number(x.isNeg)
    }
    for (let i = x.digits.length - 1; i >= 0; --i) {
      if (x.digits[i] != y.digits[i]) {
        if (x.isNeg) {
          return 1 - 2 * Number(x.digits[i] > y.digits[i])
        }
        return 1 - 2 * Number(x.digits[i] < y.digits[i])
      }
    }
    return 0
  }

  RSAUtils.biDivideModulo = function (x, y) {
    let nb = RSAUtils.biNumBits(x)
    let tb = RSAUtils.biNumBits(y)
    const origYIsNeg = y.isNeg
    let q; let
      r
    if (nb < tb) {
      // |x| < |y|
      if (x.isNeg) {
        q = RSAUtils.biCopy(bigOne)
        q.isNeg = !y.isNeg
        x.isNeg = false
        y.isNeg = false
        r = biSubtract(y, x)
        // Restore signs, 'cause they're references.
        x.isNeg = true
        y.isNeg = origYIsNeg
      } else {
        q = new BigInt()
        r = RSAUtils.biCopy(x)
      }
      return [q, r]
    }

    q = new BigInt()
    r = x

    // Normalize Y.
    let t = Math.ceil(tb / bitsPerDigit) - 1
    let lambda = 0
    while (y.digits[t] < biHalfRadix) {
      y = RSAUtils.biShiftLeft(y, 1)
      ++lambda
      ++tb
      t = Math.ceil(tb / bitsPerDigit) - 1
    }
    // Shift r over to keep the quotient constant. We'll shift the
    // remainder back at the end.
    r = RSAUtils.biShiftLeft(r, lambda)
    nb += lambda // Update the bit count for x.
    const n = Math.ceil(nb / bitsPerDigit) - 1

    let b = RSAUtils.biMultiplyByRadixPower(y, n - t)
    while (RSAUtils.biCompare(r, b) != -1) {
      ++q.digits[n - t]
      r = RSAUtils.biSubtract(r, b)
    }
    for (let i = n; i > t; --i) {
      const ri = (i >= r.digits.length) ? 0 : r.digits[i]
      const ri1 = (i - 1 >= r.digits.length) ? 0 : r.digits[i - 1]
      const ri2 = (i - 2 >= r.digits.length) ? 0 : r.digits[i - 2]
      const yt = (t >= y.digits.length) ? 0 : y.digits[t]
      const yt1 = (t - 1 >= y.digits.length) ? 0 : y.digits[t - 1]
      if (ri == yt) {
        q.digits[i - t - 1] = maxDigitVal
      } else {
        q.digits[i - t - 1] = Math.floor((ri * biRadix + ri1) / yt)
      }

      let c1 = q.digits[i - t - 1] * ((yt * biRadix) + yt1)
      let c2 = (ri * biRadixSquared) + ((ri1 * biRadix) + ri2)
      while (c1 > c2) {
        --q.digits[i - t - 1]
        c1 = q.digits[i - t - 1] * ((yt * biRadix) | yt1)
        c2 = (ri * biRadix * biRadix) + ((ri1 * biRadix) + ri2)
      }

      b = RSAUtils.biMultiplyByRadixPower(y, i - t - 1)
      r = RSAUtils.biSubtract(r, RSAUtils.biMultiplyDigit(b, q.digits[i - t - 1]))
      if (r.isNeg) {
        r = RSAUtils.biAdd(r, b)
        --q.digits[i - t - 1]
      }
    }
    r = RSAUtils.biShiftRight(r, lambda)
    // Fiddle with the signs and stuff to make sure that 0 <= r < y.
    q.isNeg = x.isNeg != origYIsNeg
    if (x.isNeg) {
      if (origYIsNeg) {
        q = RSAUtils.biAdd(q, bigOne)
      } else {
        q = RSAUtils.biSubtract(q, bigOne)
      }
      y = RSAUtils.biShiftRight(y, lambda)
      r = RSAUtils.biSubtract(y, r)
    }
    // Check for the unbelievably stupid degenerate case of r == -0.
    if (r.digits[0] == 0 && RSAUtils.biHighIndex(r) == 0) r.isNeg = false

    return [q, r]
  }

  RSAUtils.biDivide = function (x, y) {
    return RSAUtils.biDivideModulo(x, y)[0]
  }

  RSAUtils.biModulo = function (x, y) {
    return RSAUtils.biDivideModulo(x, y)[1]
  }

  RSAUtils.biMultiplyMod = function (x, y, m) {
    return RSAUtils.biModulo(RSAUtils.biMultiply(x, y), m)
  }

  RSAUtils.biPow = function (x, y) {
    let result = bigOne
    let a = x
    while (true) {
      if ((y & 1) != 0) result = RSAUtils.biMultiply(result, a)
      y >>= 1
      if (y == 0) break
      a = RSAUtils.biMultiply(a, a)
    }
    return result
  }

  RSAUtils.biPowMod = function (x, y, m) {
    let result = bigOne
    let a = x
    let k = y
    while (true) {
      if ((k.digits[0] & 1) != 0) result = RSAUtils.biMultiplyMod(result, a, m)
      k = RSAUtils.biShiftRight(k, 1)
      if (k.digits[0] == 0 && RSAUtils.biHighIndex(k) == 0) break
      a = RSAUtils.biMultiplyMod(a, a, m)
    }
    return result
  }

  $w.BarrettMu = function (m) {
    this.modulus = RSAUtils.biCopy(m)
    this.k = RSAUtils.biHighIndex(this.modulus) + 1
    const b2k = new BigInt()
    b2k.digits[2 * this.k] = 1 // b2k = b^(2k)
    this.mu = RSAUtils.biDivide(b2k, this.modulus)
    this.bkplus1 = new BigInt()
    this.bkplus1.digits[this.k + 1] = 1 // bkplus1 = b^(k+1)
    this.modulo = BarrettMu_modulo
    this.multiplyMod = BarrettMu_multiplyMod
    this.powMod = BarrettMu_powMod
  }

  function BarrettMu_modulo(x) {
    const $dmath = RSAUtils
    const q1 = $dmath.biDivideByRadixPower(x, this.k - 1)
    const q2 = $dmath.biMultiply(q1, this.mu)
    const q3 = $dmath.biDivideByRadixPower(q2, this.k + 1)
    const r1 = $dmath.biModuloByRadixPower(x, this.k + 1)
    const r2term = $dmath.biMultiply(q3, this.modulus)
    const r2 = $dmath.biModuloByRadixPower(r2term, this.k + 1)
    let r = $dmath.biSubtract(r1, r2)
    if (r.isNeg) {
      r = $dmath.biAdd(r, this.bkplus1)
    }
    let rgtem = $dmath.biCompare(r, this.modulus) >= 0
    while (rgtem) {
      r = $dmath.biSubtract(r, this.modulus)
      rgtem = $dmath.biCompare(r, this.modulus) >= 0
    }
    return r
  }

  function BarrettMu_multiplyMod(x, y) {
    /*
    x = this.modulo(x);
    y = this.modulo(y);
    */
    const xy = RSAUtils.biMultiply(x, y)
    return this.modulo(xy)
  }

  function BarrettMu_powMod(x, y) {
    let result = new BigInt()
    result.digits[0] = 1
    let a = x
    let k = y
    while (true) {
      if ((k.digits[0] & 1) != 0) result = this.multiplyMod(result, a)
      k = RSAUtils.biShiftRight(k, 1)
      if (k.digits[0] == 0 && RSAUtils.biHighIndex(k) == 0) break
      a = this.multiplyMod(a, a)
    }
    return result
  }

  const RSAKeyPair = function (encryptionExponent, decryptionExponent, modulus) {
    const $dmath = RSAUtils
    this.e = $dmath.biFromHex(encryptionExponent)
    this.d = $dmath.biFromHex(decryptionExponent)
    this.m = $dmath.biFromHex(modulus)
    // We can do two bytes per digit, so
    // chunkSize = 2 * (number of digits in modulus - 1).
    // Since biHighIndex returns the high index, not the number of digits, 1 has
    // already been subtracted.
    this.chunkSize = 2 * $dmath.biHighIndex(this.m)
    this.radix = 16
    this.barrett = new $w.BarrettMu(this.m)
  }

  RSAUtils.getKeyPair = function (encryptionExponent, decryptionExponent, modulus) {
    return new RSAKeyPair(encryptionExponent, decryptionExponent, modulus)
  }

  if (typeof $w.twoDigit === 'undefined') {
    $w.twoDigit = function (n) {
      return (n < 10 ? '0' : '') + String(n)
    }
  }

  // string after it has been converted to an array. This fixes an
  // incompatibility with Flash MX's ActionScript.
  RSAUtils.encryptedString = function (key, s) {
    const a = []
    const sl = s.length
    let i = 0
    while (i < sl) {
      a[i] = s.charCodeAt(i)
      i++
    }

    while (a.length % key.chunkSize != 0) {
      a[i++] = 0
    }

    const al = a.length
    let result = ''
    let j; let k; let
      block
    for (i = 0; i < al; i += key.chunkSize) {
      block = new BigInt()
      j = 0
      for (k = i; k < i + key.chunkSize; ++j) {
        block.digits[j] = a[k++]
        block.digits[j] += a[k++] << 8
      }
      const crypt = key.barrett.powMod(block, key.e)
      const text = key.radix == 16 ? RSAUtils.biToHex(crypt) : RSAUtils.biToString(crypt, key.radix)
      result += `${text} `
    }
    return result.substring(0, result.length - 1) // Remove last space.
  }

  RSAUtils.decryptedString = function (key, s) {
    const blocks = s.split(' ')
    let result = ''
    let i; let j; let
      block
    for (i = 0; i < blocks.length; ++i) {
      var bi
      if (key.radix == 16) {
        bi = RSAUtils.biFromHex(blocks[i])
      }
      else {
        bi = RSAUtils.biFromString(blocks[i], key.radix)
      }
      block = key.barrett.powMod(bi, key.d)
      for (j = 0; j <= RSAUtils.biHighIndex(block); ++j) {
        result += String.fromCharCode(
          block.digits[j] & 255,
          block.digits[j] >> 8,
        )
      }
    }
    // Remove trailing null, if any.
    if (result.charCodeAt(result.length - 1) == 0) {
      result = result.substring(0, result.length - 1)
    }
    return result
  }

  RSAUtils.setMaxDigits(130)
}(window))

module.exports = {
  window,
  RSAUtils: window.RSAUtils,
}
